Code Audit Decoded – What Is It and Do You Need One?

Whether you’re looking to build a digital product or upgrade an existing one, this article will get you acquainted with the concept of code audits. We explain what a code audit service is, who needs one and when, and what it typically entails.

When was the last time you took your car to the mechanic for routine maintenance? If we had to guess, we’d say it was probably at some point in the last year. This is simply good practice, even required by law in some countries. You want to know if there’s a problem before that car breaks down and leaves you stranded in the middle of nowhere.

And when was the last time you had your code thoroughly inspected? 

Code, like cars, isn’t made to last forever, no matter how well-written. It requires regular maintenance and check-ups to keep working properly. Preferably before that app starts crashing in the hands of your users. 

If you want to future-proof your digital product and make sure it continues to serve its purpose, read on.

What is a code audit, and why is it important?

Let’s start with the definition:

A software code audit is a comprehensive analysis of source code in a programming project with the intent of discovering bugs, security breaches, or violations of programming conventions.” – Wikipedia

Though the word “audit” may prompt certain negative associations, a code audit is essential for any digital product, either in development or in production. It will reveal issues that currently exist in the code and predict those that may appear in the future.

Problems with source code are just like online security issues – when everything works as intended, nobody notices them. However, if a vulnerability or a software bug opens the door for a cyber attack, you’re in a world of trouble. 

A code audit is not the same as a code review

Since both these expressions often get thrown around, it’s important to make a distinction. Code reviews usually focus on much smaller portions of code and are a part of developers’ daily work. 

For example, when implementing a new feature, one developer will review another one’s code. It’s a simple check – an additional pair of eyes examining the work done. During the code review process, they will check if the code works, if it makes sense, and how it could be improved. 

A code audit focuses on the bigger picture – the infrastructure, the architecture, vulnerability checks, along other aspects.

Who needs a code audit – and why?

Let’s make it really simple: all software needs a code audit. Whether your digital product is a web application, a mobile application, or an internal system, whether it is in development or in production, if it contains code – it needs a code audit on a regular basis. 

To start with, software development projects usually take place in an agile setting. Time to market is important, and development teams often need to ship the PoC or MVP fast. In that phase, the priority is to build something that works, so certain security and performance issues can easily go under the radar. Once the project grows and goes into production, it’s important to address them. 

Another reason is scalability. To return to the car metaphor, maybe you’re driving to work every day, and it is working fine, but maybe the circumstances will change in the future, and it will have to carry more load, drive on different roads or in different conditions, and that won’t be the case anymore. It is the same with digital products – your app may be working just fine with a couple of hundred users, but what happens if that number grows to several thousand?

However, unlike repairing your car, software is easy to change. If we anticipate potential issues, we can make adjustments before they actually happen.

How to tell if you need a code audit?

If you’re wondering whether you need one, you probably do. But let’s identify a couple of scenarios where a code audit would be recommended:

  • You have an old project with an outdated code base
  • You are experiencing security and/or performance issues
  • You are looking to add new features to your existing digital product or upgrade it in any other way 
  • Your project utilizes an older type of technology
  • You are introducing new team members to your project team or changing it altogether
  • You haven’t done one in a year

We can’t emphasize strongly enough how quickly things change in the world of software development. Ways of working change, tools change, libraries change. If a digital product has been in use for some time, chances are that parts of its code base need updating. What’s more, digital transformation is no longer a new thing. In this day and age, most companies already use some sort of digital tool. Clients who come to us with an existing digital product on their hands usually want to upgrade and improve it. However, focusing on which features to add makes no sense if you’re not adding them to a solid foundation.

Changes in the project team are another good reason to perform a code audit. New developers can have a hard time adapting to an existing code base if there are some issues with it. If the code is not readable and maintainable, they might need twice the time to get a feature to work. This is not only inefficient but will probably reflect on the overall cost of the project, not to mention team satisfaction and motivation.

Wait, isn’t that the Quality Assurance folks’ job?

Indeed, checking for bugs and errors is the whole point of quality assurance. However, QA or software testing is more focused on the end product and less on its inner workings. QA engineers will test the product from a user’s perspective, while a code audit looks at its whole structure with developer eyes. A successful code audit provides a more in-depth look and usually identifies a large number of implementation issues that the QA team would not have observed. 

Further, making sure the code base is in excellent condition will make quality assurance easier and more efficient, which benefits the whole project in the long run.

The code audit process, explained

Now that we’ve covered the what, why, and when, let’s get into the actual steps involved in a code audit.

Step 1: Becoming acquainted with the domain

In order to provide an educated opinion on the codebase, the team or person performing the audit needs to be familiar with the project domain. What is the problem that this digital product is trying to solve? Knowing the core idea helps engineers identify issues and recommend better solutions. 

Step 2: Overall assessment of the codebase

When they have a solid grasp of the product and its domain, the auditors can do a high-level assessment of the entire codebase. Knowing the main purpose of the product and its place in the industry allows them to recommend the best type of architecture, which can save clients both time and money. In this step, they also review the architecture in terms of scalability.

Step 3: Getting down to the code

After the initial high-level assessment, we will take a very close look at the source code and examine it from different perspectives. Depending on the project, it may take a whole team to audit the code thoroughly – a backend developer, a frontend developer, a DevOps expert; each examining their own domain to detect any vulnerabilities. 

Here are some aspects of the code that the auditors will be looking at.

Code readability

Is the source code well-written, and does it follow naming conventions? Are there any design patterns used? How much of the code is reused? 

Robert C. Martin, AKA Uncle Bob, the author of the book Clean Code said: “Clean code is code that is easy to understand and easy to read.” In fact, he claims that it is more important for code to be readable than for it to work. If a developer understands it, he can always make it work. And if the code doesn’t work and they can’t understand it, they also can’t fix it. 

Further, checking for duplicate code is important in case an app’s business logic needs to be changed in the future. If the same chunk of code is used in five different places, any change will need to be made in all of them, which comes with the risk of missing a place that can potentially expose a bug.

code audit - code under magnifying glass

Use of out-of-date tools

In their work, developers will often use libraries and existing implementations. As the web evolves, best practices and requests change, and so do tools. Code auditors will check if the tools used in the code are still supported and whether they are a potential security risk. 

For example, a library can be used for generating reports within an app to turn code into a spreadsheet. Auditors will ask themselves if this tool has been updated, whether it is compliant with the latest security standards, and whether it is connected to any other parts of the code because one missing update can cause a chain of unwanted events.

Security risks

While it is also possible to do a complete security audit, security is an important issue that is also checked within a code audit. 

For example, SQL injections are one of the most common web hacking techniques that can destroy a database by injecting malicious software into it through queries. The auditors will be checking for such possibilities. They will also check how passwords are stored, whether they are encrypted in the database, whether there is a time-based backup or another backup system in place, etc. 

Automated tests

No, we are not talking about the usual quality assurance tests. Often there are automated tests within the code – unit tests and integration tests. These ensure that the system works. Because the whole code base is interconnected, when something is changed with one feature, there is a strong possibility it will cause changes in other features too. With an automated test in place, the engineers working on the project will be warned about any malfunctions so they can fix them before the project goes into production. 

In a code audit, engineers will check whether there are tests in place and what is the test coverage, suggesting areas of improvement. This is especially important for large-scale enterprise applications where it is practically impossible to check the entire code and the ways in which it is interconnected. 


Few developers will say they honestly enjoy writing documentation, which makes it no less necessary or useful. Quality documentation is essential for introducing new team members to a project; it saves time and helps them work more efficiently. 

However, in the agile world, documentation may not have been prioritized while the team was racing to get an MVP out, and then simply never returned to. This is why a thorough code audit will also check how well the code is documented, and whether the documentation is up to date. Quality documentation is a lifesaver, and poor documentation can be a big hindrance.

What are the outputs of a successful code audit?

Not completely unexpected, the main output is a detailed report, usually in written form. A code audit report will state the issues found with your software and preferably identify their level of severity. A good report should also provide projections about how these issues can affect your business, predict any potential losses in regards to time and money, and suggest how these problems can be solved. 

When we’re performing a code audit as part of project work, it helps us know if there are any serious issues we need to fix before we can proceed. It also gives us a deep insight into your product’s code base, so adding extra features or upgrading the product is much easier and more efficient. 

Why not get ChatGPT to do the task?

You may be wondering how come a code audit still includes so much manual work in these times when AI is thriving. There is a very wide selection of automated code review tools that can be very useful, but can never replace a comprehensive human-led code audit. In our work, we combine both – we use tools for certain parts of the process where this is appropriate and more efficient, and check manually where needed. 

For example, static code analysis tools can help us get through thousands of lines of code to identify potential encryption issues. A tool of this type can reveal an outdated encryption algorithm, which can be a potential risk. 

In their current state of progress, AI tools can be a great asset up to a certain level of complexity. After that, AI will have a hard time understanding the project’s domain and linking different concepts and integrations together into a meaningful whole.

In these circumstances, issues can easily go under the radar. 

All AI tools, not just those used for reviewing code, tend to generalize and draw conclusions based on the most common scenarios. However, every project is unique, and without understanding its objectives and specifics, it’s impossible to make an educated decision about its code quality.

Future-proof your digital product

In the world of digital products, where technology constantly evolves and brings new innovations, a code audit is an essential process that ensures your application is stable, secure, and future-proof. 

In today’s agile development environment, time-to-market is crucial, and certain security and performance issues can easily go unnoticed during the development phase. A successful code audit is also very important for scalability – as a project grows and user numbers increase, potential vulnerabilities may emerge. 

Since we like to take good care of software, we would always recommend a code audit to anyone who owns or manages any type of a digital product, especially if that product is set for an upgrade. 

Just like taking your car for routine maintenance, it’s highly recommended to employ a code audit regularly to identify issues in the source code and prevent potential disasters down the road.